What is the Windows App Model? It's a specification of all processes in the app, how it's downloaded from Store, deployed, started, communication with the OS, how the app lifetime works, how the app capabilities and access rights are managed, how the app contracts, data roaming, device usage work, and also how the uninstallation process is handled.

Windows 10 app model is same across all supported platforms: IOT->Mobile->PC->Xbox->Hololens.

Adaptive Tile Templates - same Tile size but different content based on actual tile size.

Action Center - same look and feel shared across all platforms. Alarms and Reminders working again, can be viewed in Action Center. Action Center Change Trigger for updating Live Tiles when notification is removed.